This application is based on Korean patent application No. 99-47436 filed on Oct. 29, 1999, the disclosure of which is incorporated herein by reference.
(a) Field of the Invention
The present invention relates to a vibration attenuating apparatus and method, more particularly, to a vibration attenuating apparatus and method which includes an electrically controlled damping means changing the damping coefficient of a damper spring for preventing vibration transmitting from an engine to a transmission unit.
(b) Description of the Related Art
Generally, as shown in FIG. 6, vehicles have an engine 112 for generating driving power, and a transmission unit 114 for changing the torque and speed of the engine. The transmission unit is classified as an automatic transmission unit or a manual transmission unit. The manual transmission unit has a clutch for controlling the connection of the engine power to the transmission unit.
The clutch includes a clutch cover 118 connecting to the flywheel 116, clutch disc 120 mounted between the clutch cover 118 and flywheel 116 for transmitting the engine output to the transmission unit by way of a clutch shaft, and a release bearing 122 for transmitting the pedal depressing force by way of a release fork.
FIG. 7 shows the detailed structure of the clutch disc 120 according to the prior art. The clutch disc 120 include clutch plates 124, a clutch hub 126 splinedly connected to the clutch shaft, frictional facings 128 mounted on front and rear surface of the clutch plates 124, and damper springs 130 mounted on the clutch plates 124 for attenuating the rotating vibration of an engine.
When the torque variation of an engine increases above the normal torque range, the abnormal torque variation generates torsional vibration in the driving system, including the transmission unit, and makes the whole car body vibrate severely.
To prevent transmitting the abnormal vibration to the driving system, damper springs are mounted in the clutch disc. However, since damper springs have fixed damping coefficients, they can not flexibly respond to the variation of engine torque, and thus they cannot attenuate the abnormal vibration effectively. On the other hand, damper springs with a high damping coefficient can be used, but a high damping coefficent of the damper spring negatively affects the driveability of vehicles.
Accordingly, it is an object of the present invention to provide a vibration attenuating apparatus and method which can prevent transmission of abnormal vibration to a transmission unit without negatively affecting driveability.
This and other objects may be achieved by a vibration attenuating apparatus for use on damper springs of a clutch disc including clutch plates, a clutch hub splinedly connected to a clutch shaft, frictional facings mounted on front and rear surfaces of the clutch plates, and damper springs mounted on the clutch plates.
The vibration attenuating apparatus includes variable damping means inserted into each damper spring, controlling a damping coefficient of the damper springs in accordance with an intensity of an electric current provided by an electronic control unit. The variable damping means may include a chamber inserted into the damper spring, and electro-rheological fluid filling up said chamber and controlling the damping force of said damper springs by way of shear resistance due to an anisotropic characteristic thereof.
According to the invention, there is also provided a method for the electronic control unit to control the vibration attenuating apparatus for use on the damper springs of a clutch disc including the first step of detecting a speed of a vehicle and a torque variation of the engine. When the detected speed of the vehicle is within a predetermined speed range and the detected torque of the engine is above a standard torque range in relation to the speed of vehicle, the electronic control unit provides an electric current to the electro-rheological fluid which is inserted into the damper spring of the clutch disc. Then, the electronic control unit detects the torque variation of the transmission. Finally, when the detected torque of the transmission is within a standard transmission torque range in relation to the speed of the vehicle, the electronic control unit stops the electric current from flowing to the electro-rheological fluid. However, when the detected torque of the transmission deviates from the standard transmission torque range in relation to the speed of the vehicle, the electronic control unit increases the intensity of the electric current by a predetermined amount, then detects the torque variation of the transmission again.
The predetermined speed range of vehicles in the step of providing electric current may be from 20 km/h to 60 km/h.